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Post packaging operations

Checkweighing

To aid in controlling and recording pack weights, checkweighing machines are commonly sited immediately after each wrapping machine so that every pack is weighed. These machines can be set to reject any pack that is below the minimum weight. Other types of checkweigher can be set to record average weights over given periods, the standard deviations of the weights, and to reject packs that are below or above given limits. In addition to satisfying legal requirements these machines therefore are useful for detecting packs that may not have the full number of biscuits due to malfunction of the biscuit feeding systems.

Foreign matter detection

Processing of food always involves the risk of inclusion of foreign matter. A few materials such as slivers of metal, glass or toxic chemicals may be dangerous to health, but mostly the effect on consumers is one of revulsion rather than danger. Every means possible should be taken to ensure that foreign matter does not become included and that which does is detected before the product leaves the factory.

Foreign matter in biscuits is more likely to lead to prosecution and bad publicity than any other defect of the company or its products.

Foreign matter such as glass, stone and metal have significantly different densities from biscuits and this property has been used in the development of detection methods using, for example, X-rays. However, at present, there is no widely used instrument for every pack scanning of biscuit densities. The problem is that pieces will probably be small and detection at the speeds involved must be linked to automatic rejection.

Metal detectors capable of finding and rejecting packs containing particles of metal one millimetre or more in size are commonplace and it is recommended that each production line should be equipped to scan every pack after the wrapping machine. The quality control department should be intimately involved in the use of metal detectors, not only to ensure that their performance is checked regularly according to at least the manufacturers' recommendations, but also to see that packs rejected are reliably collected and subsequently examined for the offending metal. Since prevention is the aim, it is worth trying to identify the source of each piece of metal, by consultation with engineers if necessary, so that action aimed at preventing further cases may be taken. Attention at this stage as well as protecting the company reputation may also provide early indication of the need for machine maintenance.

Palletisation

Packets of biscuits are usually collated in cases, fiberites, for storage and transportation. These cases are stacked on floor pallets and these are then moved with fork lift trucks or similar vehicle. The orientation of the cases on the pallet needs some careful thought to achieve a stable structure so that individual cases do not fall off and to ensure that damage due to pressure is minimal. Unless the cases are square in basal shape they can be stacked like house bricks so that they overlap gaps and thus lock together. Some additional locking of the cases can be achieved by placing sheets of paper between the layers. The cases are normally stacked to a height of about 2 metres which is 6 or 7 cases high. Remember that the strength of fiberites is only good if they are placed upright due to the orientation of the fluting of the board. Additional locking of the cases in a pallet may be done by wrapping shrinkwrap film around the completely loaded pallet or with straps.

It is important that handling of the cases is such that the biscuits in the packs within are not damaged. Common causes of damage are from cases placed so that they overlap the area of the pallet and pallets are stacked too high one upon another creating excessive pressure on the bottom cases. If very high stacking is needed chose fiberites of suitable mechanical strength.

It is recommended that the orientation and stacking of cases on pallets is recorded on the Process Standards Document so that operators know what is required for each product. This not only ensures that the correct number of cases is put on a pallet (useful for easy checking of output and stocks) but also for optimum protection of biscuits from mechanical damage during transportation and storage.